气道上皮再生对肺移植后闭塞性气道疾病的影响

Role of reepithelization in the development of obliterative airway disease after lung transplantation

目的探讨气道上皮再生对肺移植后闭塞性气道疾病（OAD）的影响。方法以Balb／c小鼠的气管和左主支气管构成的连续气道为移植物，原位移植给C57BL／6小鼠，供者的气管与受者头侧的气管断端行端端吻合，供者的右支气管残端与受者气管的另一断端行端端吻合，左主支气管的残端结扎，形成盲端（非结扎组），部分受者在此基础上将其左主支气管起始部也予以结扎（结扎组）。术后28d切取移植物，HE染色评价OAD的发生情况、气道上皮的完整性和分化程度、黏膜下炎症细胞浸润和纤维组织增生情况；应用形态学定量分析软件测量固有层与软骨的比值（LCR）、黏膜下层纤维组织的面积（以象素表示）以及气道上皮中纤毛上皮的比例；免疫组织化学染色鉴定气道上皮的表型。结果两个组的气管段以及非结扎组的支气管管腔通畅，上皮完整，黏膜下可见炎症细胞浸润和纤维组织增生，未见OAD改变；而结扎组的支气管中可见大量纤维组织增生致管腔完全闭塞，上皮消失，软骨塌陷，呈现明显OAD改变。非结扎组的气管和支气管以及结扎组的气管的LCR明显高于正常气管（P〈0．01）；结扎组的气管和支气管、非结扎组的气管和支气管固有膜内的纤维组织面积明显超过正常气管（P〈0．05），结扎组的支气管固有膜内的纤维组织面积明显大于非结扎组的支气管（P〈0．05）；非结扎组的气管和支气管以及结扎组的气道上皮中纤毛上皮的比例明显低于正常气管上皮（P〈0．05）；非结扎组的支气管纤毛上皮比例明显低于非结扎组的气管和结扎组的气管（P〈0．01）。两个组的气管和非结扎组的支气管上皮为受者上皮表型，而结扎组支气管无受者上皮存在。结论移植气道的上皮经再上皮化，其上皮表型改变，抗原性降低，并且由于该再生的上皮对黏膜下纤维组织的增生有抑制作用，从而预防了OAD的发生。

Objective To investigate the role of airway reepithelization in the development of obliterative airway disease （OAD） after lung transplantation. Methods Donor allograft was obtained as Balb/c trachea and its connecting left bronchi, and it was subsequently orthotopically transplanted into recipient C57BL/6 mouse. Both ends of the donor trachea were anastmosed to the recipient in end- to-end mode, and the bronchial branch was ligated distally. In the ligated group, the proximal end of the bronchi was ligated; it was otherwise left open in the unligated group. Allografts were harvested on postoperative day 28, and were examined for OAD manifestations, epithelium integrity and differentiation, submueous lymphocyte infiltration, and fibroproliferation. LCR, submucous fibrous tissue area and ciliated epithelium proportion were measured with computerized morphometry. Epithelium phenotype was examined by immunohistochemical stain. Results Tacheal allografts and unligated bronchi maintained luminal patency and integrated epithelium, while ligated bronchial allografts were obliterated with fibrous tissue, which was characteristic of OAD. LCR and lamina propria of the donor trachea and unligated bronchi were significantly higher than normal tracha （P〈0. 01 and P〈0. 05）. However, ciliated epithelium proportion of the tracheal allografts was intermediate between normal trachea and ligated bronchi （_P〈0. 05 and P〈0. 01 ）. Immunohistochemical stain revealed recipient phenotype in both the tracheal and unligated bronchial allografts; no recipient phenotype expression was noted in the ligated bronchial allografts. Conclusion Reepithelization with recipient-drived mucosa prevents OAD development in orthotopic tracheal and unligated bronchial allografts by changing the epithelium phenotype and regulating fibroblasts proliferation in the lamina propria.